Plotting convolved Uniform distributions using MATLAB- looking for an EXPERT

Assume X ∼ Uniform[5, 10] subject to (i) additive measurement error Z = X + Y ,
with σ = kX and Y is zero mean gaussian errors,(ii) multiplicative errors, Z = X × Y
and Y is lognormal error distribution with mean and sigma i.e Y ∼ lognormal(µ, σ).
In each case consider 4 instances:k=0.05,0.1,0.15,0.25 and in each case set k = σ. plot
the convolved PDFs of f(z) for case (i) and for case(ii) bear in mind the constraint that
µ = −
σ
2
2
.
the PDFs are:
Case(i):If Z = X + Y and X follows the uniform distribution and Y follows the zero
mean Gaussian distribution,